Re: Yet Another G5PC MOD :) Yes I know...
I'll toss this here so others can also benefit:
For sanding, I usually use regular wet/dry sandpaper and a wood block for finishing work. Sanding sponges are good for curved stuff, but if you're trying to flatten a surface out and remove irregularities you will find the sponge conforms and will sand down in the dips. A wood block planes over the irregularities and take off the high points.
The way I would do any of the added relief items on the outside of the case would be by casting them in resin. (Getting started with casting resin is a bit costly, but if you're doing a lot of mods it opens up a lot of cool things you can do by duplicating your work.) You could then mount the resin parts with screws, rivets or just double stick tape (servo tape for RC cars is the best).
Make your original part out of anything you want to work with. Basswood is perfect for the flatter shapes and can be cut and sanded extremely easily. You can also add plastic and other items as well. Bondo or clay will also work. You load up the basswood with sanding sealer, sand it, prime it, wet sand that so it's got a nice surface. Make sure everything's well smoothed and doesn't have a porous surface. Then cast a mold of that part in RTV silicone. TAP Plastics sells kits and supplies for casting. Some hardware stores carry similar. You'll have to look around for similar in your area. Basically, the mold is rubbery. You then cast resin (clear plasticky stuff) into that mold. Once cured, the molds are easy to peel off without damaging them, even molds with some overhang since the silicone is stretchy.
You will need:
1. Your original part, cleaned and sealed so it's not porous.
2. Silicone mold compound
3. Mold release agent for silicone molds
4. Casting resin
5. A small box to cast the silicone mold in (you can use the box as support for the mold when you cast the resin parts, then remove the box to make the mold flexible.
There are tutorials online for doing castings like this. It's not difficult if you prep correctly. You can make more than one casting from the same mold, and it makes for a very durable cast part. Added bonus, if you use clear resin, well... it's clear. You can add lighting inside it.
If you want something that's really integral to the side of the case and shows no seam where it attaches, you should do it out of metal if possible. You can form the shape from bondo, but it's not ideal. "Bondo", also referred to as "car body cheese" has a nasty habit of just falling off of the metal surface. It's best use is to act as a final smoother for a surface, not to fill big stuff. Build your sloping item out of metal or any other suitable base that is well attached with screws or rivets, then smooth the joints out with the bondo. Do this directly on bare metal. Alternatively, cut the metal case side and fold it out to form your slope, then add material as needed to close it up again.
When working with Bondo, remember that there's a short working time before you can't spread it around anymore. Starts out like peanut butter. Use this working time to get it close to your shape. Then it hardens up but is still a bit soft. Get to grinding as soon as possible if there's any spots you want to smooth out. After that softer time, about 30 minutes, it gets extremely hard. At this point, you're into blocking and fine sanding only as it's very tough to make a dent in it with anything short of air impact tools. Definitely try the stuff out on a scrap and just play with it to get a feel for it. It's got a bit of a learning curve that'll be a surprise the first time you use it.
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Originally Posted by jdbnsn
